High efficiency magnetic link for implantable devices

ABSTRACT

Systems and devices for a high-efficiency magnetic link for implantable devices are disclosed herein. These devices can include a charging coil located in the implantable device and a charging coil located in a charge head of a charger. The charging coils can each include an elongate core and wire windings wrapped around a longitudinal axis of the elongate core. The charging coil of the charge head can be attached to a rotatable mount, which can be used to align the longitudinal axis of the charging coil of the charge head with longitudinal axis of the implantable device such that the axes of the charging coils are parallel.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/446,291, entitled “HIGH EFFICIENCY MAGNETIC LINK FOR IMPLANTABLEDEVICES,” and filed on Jul. 29, 2014, which claims the benefit of U.S.Provisional Application No. 61/859,478, entitled “HIGH EFFICIENCYMAGNETIC LINK FOR IMPLANTABLE DEVICES,” and filed on Jul. 29, 2013, theentirety of each which are hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

The prevalence of use of medical devices in treating ailments isincreasing with time. In many instances, and as these medical devicesare made smaller, these medical devices are frequently implanted withina patient. While the desirability of implantable devices is increasingas the size of the devices has decreased, the implantation process stillfrequently requires complicated surgery which can expose the patient tosignificant risks and protracted recovery times. In light of this,further methods, systems, and devices are desired to increase the easeof use of implantable and/or implanted medical devices.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present disclosure relates to a method of charging animplantable device. The method includes positioning a charging headincluding a transmitting coil attached to a rotatable mount proximate toan implantable device including a receiving coil, determining a firstorientation of the transmitting coil with respect to the receiving coil,and rotating the rotatable mount and the thereto attached transmittingcoil until the transmitting coil has a second orientation with respectto the receiving coil.

In some embodiments, the transmitting coil has a longitudinal axis andat least one wire wrapped around the longitudinal axis. In someembodiments, the receiving coil has a longitudinal axis and at least onewire wrapped around the longitudinal axis.

In some embodiments, determining the first orientation of thetransmitting coil with respect to the receiving coil includesdetermining an angle between the longitudinal axis of the transmittingcoil with respect to the longitudinal axis of the receiving coil. Insome embodiments, the angle between the longitudinal axis of thetransmitting coil is non-parallel with the longitudinal axis of thereceiving coil in the first orientation. In some embodiments, an anglebetween the longitudinal axis of the transmitting coil and thelongitudinal axis of the receiving coil in the second orientation isless than the angle between the longitudinal axis of the transmittingcoil and the longitudinal axis of the receiving coil in the firstorientation. In some embodiments, the charging efficiency in the firstorientation is less than the charging efficiency in the secondorientation.

In some embodiments, rotating the rotatable mount and the theretoattached transmitting coil until the transmitting coil has a secondorientation with respect to the receiving coil includes determining whenan angle between the longitudinal axis of the transmitting coil and thelongitudinal axis of the charging coil is minimized. In someembodiments, the second orientation is reached when the angle betweenthe longitudinal axis of the transmitting coil and the longitudinal axisof the charging coil is minimized.

One aspect of the present disclosure relates to an implantable device.The implantable device includes a processor that can control theoperation of the implantable device and can generate a plurality ofelectrical impulses for stimulating a peripheral nerve, a lead that canbe placed proximate to a peripheral nerve, an energy storage device thatcan store energy, and a charging coil having an elongate core having afirst end, and second end, and a longitudinal axis extendingtherebetween, and a wire wrapped in a plurality of coils around theelongate core and the longitudinal axis of the elongate core.

In some embodiments, the wire can be litz wire. In some embodiments, theelongate core can be made of a soft ferrite material. In someembodiments, the charging coil has a Q factor of at least 70, and insome embodiments, the charging coil has a Q factor of at least 80. Insome embodiments, the charging coil further includes a capacitorelectrically connected to the wire, which capacitor can be a high Q COGcapacitor. In some embodiments, the capacitor is located on the chargingcoil, and in some embodiments, the capacitor is located proximate to thecharging coil. In some embodiments, the capacitor is positioned so as tocreate a high Q tank circuit.

One aspect of the present disclosure relates to a charging head. Thecharging head includes a contact surface, a rotatable mount positioned adistance from the contact surface and rotatable with respect to thecontact surface, and a charging coil attached to the rotatable mount.

In some embodiments, the charging coil includes an elongate core havinga first end, and a second end, and a longitudinal axis extendingtherebetween, and a wire wrapped in a plurality of coils around theelongate core and the longitudinal axis of the elongate core. In someembodiments, the elongate core includes a first foot located at thefirst end and a second foot located at the second end.

In some embodiments, the first and second feet extend towards thecontact surface. In some embodiments, the contact surface can be a trackthat can receive the first and second feet and to allow the rotation ofthe rotatable mount and the thereto attached charging coil. In someembodiments, the charging coil can rotate at least 180 degrees.

In some embodiments, the wire can be litz wire. In some embodiments, theelongate core can be a soft ferrite material. In some embodiments, thecharging coil has a Q factor of at least 50, and in some embodiments,the charging coil has a Q factor of at least 100.

One aspect of the present disclosure relates to a charging system. Thecharging system includes an implantable device having a receiving coil.In some embodiments, the receiving coil can have an elongate core havinga first end, a second end, and a longitudinal axis extendingtherebetween, and a wire wrapped in a plurality of coils around theelongate core and the longitudinal axis of the elongate core. Thecharging system can include a charging head having a transmitting coil.In some embodiments, the transmitting coil can include an elongate corehaving a first end, a second end, and a longitudinal axis extendingtherebetween, and a wire wrapped in a plurality of coils around theelongate core and the longitudinal axis of the elongate core.

In some embodiments, the receiving coil can be a capacitor electricallyconnected to the wire of the receiving coil. In some embodiments, thecharging head can include a rotatable mount. In some embodiments, thetransmitting coil is attached to the rotatable mount. In someembodiments, the rotatable mount is rotatable between a first positionand a second position. In some embodiments, the rotatable mount islockable in the first position and in the second position.

In some embodiments, the charging system can include circuitry that candetect an angular position of the receiving coil with respect to thetransmitting coil. In some embodiments, the circuitry that can detect anangular position of the receiving coil with respect to the transmittingcoil are in the charging head.

One aspect of the present disclosure relates to a method of charging animplantable device. The method includes positioning an external chargeron an outer surface of a person's body proximate an implanted electricalpulse generator, the external charger including a housing and chargingcoil, the charging coil supported inside the housing such that thecharging coil is rotatable inside of the housing, the implantedelectrical pulse generator including a charging coil, fixing theposition of the external charger on the outer surface of the person'sbody, and while the external charger is fixed on the outer surface ofthe person's body, rotating the charging coil of the external charger tochange an orientation of the charging coil of the external chargerrelative to the charging coil of the implanted electrical pulsegenerator.

In some embodiments, the implanted electrical pulse generator furthercan be at least one electrode implanted proximate a peripheral nerve ofthe person.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating various embodiments, are intended for purposes ofillustration only and are not intended to necessarily limit the scope ofthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of one embodiment of an implantableneurostimulation system.

FIG. 2 is a schematic illustration of one embodiment ofinterconnectivity of the implantable neurostimulation system.

FIG. 3 is a schematic illustration of one embodiment of the architectureof the external pulse generator and/or of the implantable pulsegenerator that is a part of the implantable neurostimulation system.

FIG. 4 is a schematic illustration of one embodiment of the charger thatis a part of the implantable neurostimulation system.

FIG. 5 is a perspective view of one embodiment of an implantable pulsegenerator and a charger.

FIG. 6 is a perspective view of one embodiment of a charging coil thatcan be used in an implantable pulse generator.

FIG. 7 is a perspective view of one embodiment of a charging coil thatcan be used in a charger.

FIG. 8 is a section view of one embodiment of an implantable pulsegenerator and a charger.

FIG. 9 is a flowchart illustrating one embodiment of a process forproviding an alignment indicator for a charger.

FIG. 10 is a flowchart illustrating one embodiment of a process forproviding an alignment indicator for a charger based on detectedvariations in measured voltage and current.

FIG. 11 is a flowchart illustrating one embodiment of a process in whichmovement of a charger is detected during the charging process.

FIG. 12 is a flowchart illustrating one embodiment of a process foradjusting the rotatable mount of a charger.

In the appended figures, similar components and/or features may have thesame reference label. Where the reference label is used in thespecification, the description is applicable to any one of the similarcomponents having the same reference label.

DETAILED DESCRIPTION OF THE INVENTION

A significant percentage of the Western (EU and US) population isaffected by Neuropathic pain (chronic intractable pain due to nervedamage). In many people, this pain is severe. There are thousands ofpatients that have chronic intractable pain involving a nerve.Neuropathic pain can be very difficult to treat with only half ofpatients achieving partial relief. Thus, determining the best treatmentfor individual patients remains challenging. Conventional treatmentsinclude certain antidepressants, anti-epileptic drugs and opioids.However, side effects from these drugs can be detrimental. In some ofthese cases, electrical stimulation can provide effective treatment ofthis pain without the drug-related side effects.

A spinal cord stimulator is a device used to deliver pulsed electricalsignals to the spinal cord to control chronic pain. Because electricalstimulation is a purely electrical treatment and does not cause sideeffects similar to those caused by drugs, an increasing number ofphysicians and patients favor the use of electrical stimulation overdrugs as a treatment for pain. The exact mechanisms of pain relief byspinal cord stimulation (SCS) are unknown. Early SCS trials were basedon the Gate Control Theory, which posits that pain is transmitted by twokinds of afferent nerve fibers. One is the larger myelinated Aδ fiber,which carries quick, intense-pain messages. The other is the smaller,unmyelinated “C” fiber, which transmits throbbing, chronic painmessages. A third type of nerve fiber, called Aβ, is “non-nociceptive,”meaning it does not transmit pain stimuli. The gate control theoryasserts that signals transmitted by the Aδ and C pain fibers can bethwarted by the activation/stimulation of the non-nociceptive Aβ fibersand thus inhibit an individual's perception of pain. Thus,neurostimulation provides pain relief by blocking the pain messagesbefore they reach the brain.

SCS is often used in the treatment of failed back surgery syndrome, achronic pain syndrome that has refractory pain due to ischemia. SCScomplications have been reported in a large portion, possibly 30% to40%, of all SCS patients. This increases the overall costs of patientpain management and decreases the efficacy of SCS. Common complicationsinclude: infection, hemorrhaging, injury of nerve tissue, placing deviceinto the wrong compartment, hardware malfunction, lead migration, leadbreakage, lead disconnection, lead erosion, pain at the implant site,generator overheating, and charger overheating. The occurrence rates ofcommon complications are surprisingly high: including lead extensionconnection issues, lead breakage, lead migration and infection.

Peripheral neuropathy, another condition that can be treated withelectrical stimulation, may be either inherited or acquired. Causes ofacquired peripheral neuropathy include physical injury (trauma) to anerve, viruses, tumors, toxins, autoimmune responses, nutritionaldeficiencies, alcoholism, diabetes, and vascular and metabolicdisorders. Acquired peripheral neuropathies are grouped into three broadcategories: those caused by systemic disease, those caused by trauma,and those caused by infections or autoimmune disorders affecting nervetissue. One example of an acquired peripheral neuropathy is trigeminalneuralgia, in which damage to the trigeminal nerve (the large nerve ofthe head and face) causes episodic attacks of excruciating,lightning-like pain on one side of the face.

A high percentage of patients with peripheral neuropathic pain do notbenefit from SCS for various reasons. However, many of these patientscan receive acceptable levels of pain relief via direct electricalstimulation to the corresponding peripheral nerves. This therapy iscalled peripheral nerve stimulation (PNS). As FDA approved PNS deviceshave not been commercially available in the US market, Standard spinalcord stimulator (SCS) devices are often used off label by painphysicians to treat this condition. A significant portion of SCS devicesthat have been sold may have been used off-label for PNS.

As current commercially-available SCS systems were designed forstimulating the spinal cord and not for peripheral nerve stimulation,there are more device complications associated with the use of SCSsystems for PNS than for SCS. Current SCS devices (generators) are largeand bulky. In the event that an SCS is used for PNS, the SCS generatoris typically implanted in the abdomen or in the lower back above thebuttocks and long leads are tunneled across multiple joints to reach thetarget peripheral nerves in the arms, legs or face. The excessivetunneling and the crossing of joints leads to increased post-surgicalpain and higher device failure rates. Additionally, rigid leads can leadto skin erosion and penetration, with lead failure rates being far toohigh within the first few years of implantation. Many or even mostcomplications result in replacement surgery and even multiplereplacement surgeries in some cases.

One embodiment of an implantable neurostimulation system 100 is shown inFIG. 1, which implantable neurostimulation system 100 can be, forexample, a peripherally-implantable neurostimulation system 100. In someembodiments, the implantable neurostimulation system 100 can be used intreating patients with, for example, chronic, severe, refractoryneuropathic pain originating from peripheral nerves. In someembodiments, the implantable neurostimulation system 100 can be used toeither stimulate a target peripheral nerve or the posterior epiduralspace of the spine.

The implantable neurostimulation system 100 can include one or severalpulse generators. The pulse generators can comprise a variety of shapesand sizes, and can be made from a variety of materials. In someembodiments, the one or several pulse generators can generate one orseveral non-ablative electrical pulses that are delivered to a nerve tocontrol pain. In some embodiments, these pulses can have a pulseamplitude of between 0-1,000 mA, 0-100 mA, 0-50 mA, 0-25 mA, and/or anyother or intermediate range of amplitudes. One or more of the pulsegenerators can include a processor and/or memory. In some embodiments,the processor can provide instructions to and receive information fromthe other components of the implantable neurostimulation system 100. Theprocessor can act according to stored instructions, which storedinstructions can be located in memory, associated with the processor,and/or in other components of the implantable neurostimulation system100. The processor can, in accordance with stored instructions, makedecisions. The processor can comprise a microprocessor, such as amicroprocessor from Intel® or Advanced Micro Devices, Inc.®, or thelike.

In some embodiments, the stored instructions directing the operation ofthe processor may be implemented by hardware, software, scriptinglanguages, firmware, middleware, microcode, hardware descriptionlanguages, and/or any combination thereof. When implemented in software,firmware, middleware, scripting language, and/or microcode, the programcode or code segments to perform the necessary tasks may be stored in amachine readable medium such as a storage medium. A code segment ormachine-executable instruction may represent a procedure, a function, asubprogram, a program, a routine, a subroutine, a module, a softwarepackage, a script, a class, or any combination of instructions, datastructures, and/or program statements. A code segment may be coupled toanother code segment or a hardware circuit by passing and/or receivinginformation, data, arguments, parameters, and/or memory contents.Information, arguments, parameters, data, etc. may be passed, forwarded,or transmitted via any suitable means including memory sharing, messagepassing, token passing, network transmission, etc.

In some embodiments, the memory of one or both of the pulse generatorscan be the storage medium containing the stored instructions. The memorymay represent one or more memories for storing data, including read onlymemory (ROM), random access memory (RAM), magnetic RAM, core memory,magnetic disk storage mediums, optical storage mediums, flash memorydevices and/or other machine readable mediums for storing information.In some embodiments, the memory may be implemented within the processoror external to the processor. In some embodiments, the memory can be anytype of long term, short term, volatile, nonvolatile, or other storagemedium and is not to be limited to any particular type of memory ornumber of memories, or type of media upon which memory is stored. Insome embodiments, the memory can include, for example, one or both ofvolatile and nonvolatile memory. In one specific embodiment, the memorycan include a volatile portion such as RAM memory, and a nonvolatileportion such as flash memory.

In some embodiments, one of the pulse generators can be an externalpulse generator 102 or an implantable pulse generator 104. The externalpulse generator 102 can be used to evaluate the suitability of a patientfor treatment with the implantable neurostimulation system 100 and/orfor implantation of an implantable pulse generator 104.

In some embodiments, one of the pulse generators can be the implantablepulse generator 104, which can be sized and shaped, and made of materialto allow implantation of the implantable pulse generator 104 inside of abody. In some embodiments, the implantable pulse generator 104 can besized and shaped so as to allow placement of the implantable pulsegenerator 104 at any desired location in a body, and in someembodiments, placed proximate to a peripheral nerve such that leads(discussed below) are not tunneled across joints and/or such thatextension cables are not needed.

The implantable pulse generator 104 can include one or several energystorage features. In some embodiments, these features can be configuredto store energy, such as, for example, electric energy, that can be usedin the operation of the implantable pulse generator 104. These energystorage features can include, for example, one or several batteries,including rechargeable batteries, one or several capacitors, one orseveral fuel cells, or the like.

In some embodiments, the electrical pulses generated by the pulsegenerator can be delivered to one or several nerves 110 and/or to tissueproximate to one or several nerves 110 via one or several leads. Theleads can include conductive portions, such as electrodes or contactportions of electrodes, and non-conductive portions. The leads can havea variety of shapes, can be a variety of sizes, and can be made from avariety of materials, which size, shape, and materials can be dictatedby the application or other factors. In some embodiments, the leads canbe implanted proximate to a peripheral nerve. In one embodiment, boththe implantable pulse generator 104 and the leads can be implanted in aperipheral portion of the patient's body, and can be configured todeliver one or several electrical pulses to the peripheral nerve.

In some embodiments, the leads can include an anodic lead 106 and/or acathodic lead 108. In some embodiments, the anodic lead 106 and thecathodic lead 108 can be identical leads, but can receive pulses ofdifferent polarity from the pulse generator.

In some embodiments, the leads can connect directly to the pulsegenerator, and in some embodiments, the leads can be connected to thepulse generator via a connector 112 and a connector cable 114. Theconnector 112 can comprise any device that is able to electricallyconnect the leads to the connector cable 114. Likewise, the connectorcable can be any device capable of transmitting distinct electricalpulses to the anodic lead 106 and the cathodic lead 108.

In some embodiments, the implantable neurostimulation system 100 caninclude a charger 116 that can be configured to recharge the implantablepulse generator 104 when the implantable pulse generator 104 isimplanted within a body. The charger 116 can comprise a variety ofshapes, sizes, and features, and can be made from a variety ofmaterials. Like the pulse generators 102, 104, the charger 116 caninclude a processor and/or memory having similar characteristics tothose discussed above. In some embodiments, the charger 116 can rechargethe implantable pulse generator 104 via an inductive coupling.

In some embodiments, one or several properties of the electrical pulsescan be controlled via a controller. In some embodiments, theseproperties can include, for example, the frequency, strength, pattern,duration, or other aspects of the timing and magnitude of the electricalpulses. In one embodiment, these properties can include, for example, avoltage, a current, or the like. In one embodiment, a first electricalpulse can have a first property and a second electrical pulse can have asecond property. This control of the electrical pulses can include thecreation of one or several electrical pulse programs, plans, orpatterns, and in some embodiments, this can include the selection of oneor several pre-existing electrical pulse programs, plans, or patterns.In the embodiment depicted in FIG. 1, the implantable neurostimulationsystem 100 includes a controller that is a clinician programmer 118. Theclinician programmer 118 can be used to create one or several pulseprograms, plans, or patterns and/or to select one or several of thecreated pulse programs, plans, or patterns. In some embodiments, theclinician programmer 118 can be used to program the operation of thepulse generators including, for example, one or both of the externalpulse generator 102 and the implantable pulse generator 104. Theclinician programmer 118 can comprise a computing device that canwiredly and/or wirelessly communicate with the pulse generators. In someembodiments, the clinician programmer 118 can be further configured toreceive information from the pulse generators indicative of theoperation and/or effectiveness of the pulse generators and the leads.

In some embodiments, the controller of the implantable neurostimulationsystem 100 can include a patient remote 120. The patient remote 120 cancomprise a computing device that can communicate with the pulsegenerators via a wired or wireless connection. The patient remote 120can be used to program the pulse generator, and in some embodiments, thepatient remote 120 can include one or several pulse generation programs,plans, or patterns created by the clinician programmer 118. In someembodiments, the patient remote 120 can be used to select one or severalof the pre-existing pulse generation programs, plans, or patterns and toselect, for example, the duration of the selected one of the one orseveral pulse generation programs, plans, or patterns.

Advantageously, the above outlined components of the implantableneurostimulation system 100 can be used to control and provide thegeneration of electrical pulses to mitigate patient pain.

With reference now to FIG. 2, a schematic illustration of one embodimentof interconnectivity of the implantable neurostimulation system 100 isshown. As seen in FIG. 2, several of the components of the implantableneurostimulation system 100 are interconnected via network 110. In someembodiments, the network 110 allows communication between the componentsof the implantable neurostimulation system 100. The network 110 can be,for example, a local area network (LAN), a wide area network (WAN), awired network, a custom network, wireless network, a telephone networksuch as, for example, a cellphone network, the Internet, the World WideWeb, or any other desired network or combinations of different networks.In some embodiments, the network 110 can use any desired communicationand/or network protocols. The network 110 can include any communicativeinterconnection between two or more components of the implantableneurostimulation system 100. In one embodiment, the communicationsbetween the devices of the implantable neurostimulation system 100 canbe according to any communication protocol including, for example thosecovered by Near Field Communication (NFC), Bluetooth, or the like. Insome embodiments, different components of the system may utilizedifferent communication networks and/or protocols.

With reference now to FIG. 3, a schematic illustration of one embodimentof the architecture of the external pulse generator 102 and/or of theimplantable pulse generator 104 is shown. In some embodiments, each ofthe components of the architecture of the one of the pulse generators102, 104 can be implemented using the processor, memory, and/or otherhardware component of the one of the pulse generators 102, 104. In someembodiments, the components of the architecture of the one of the pulsegenerators 102, 104 can include software that interacts with thehardware of the one of the pulse generators 102, 104 to achieve adesired outcome.

In some embodiments, the pulse generator 102/104 can include, forexample, a network interface 300, or alternatively, a communicationmodule. The network interface 300, or alternatively, the communicationmodule, can be configured to access the network 110 to allowcommunication between the pulse generator 102, 104 and the othercomponents of the implantable neurostimulation system 100. In someembodiments, the network interface 300, or alternatively, acommunication module, can include one or several antennas and softwareconfigured to control the one or several antennas to send information toand receive information from one or several of the other components ofthe implantable neurostimulation system 100.

The pulse generator 102, 104 can further include a data module 302. Thedata module 302 can be configured to manage data relating to theidentity and properties of the pulse generator 102, 104. In someembodiments, the data module can include one or several databases thatcan, for example, include information relating to the pulse generator102, 104 such as, for example, the identification of the pulsegenerator, one or several properties of the pulse generator 102, 104, orthe like. In one embodiment, the data identifying the pulse generator102, 104 can include, for example, a serial number of the pulsegenerator 102, 104 and/or other identifier of the pulse generator 102,104 including, for example, a unique identifier of the pulse generator102, 104. In some embodiments, the information associated with theproperty of the pulse generator 102, 104 can include, for example, dataidentifying the function of the pulse generator 102, 104, dataidentifying the power consumption of the pulse generator 102, 104, dataidentifying the charge capacity of the pulse generator 102, 104 and/orpower storage capacity of the pulse generator 102, 104, data identifyingpotential and/or maximum rates of charging of the pulse generator 102,104, and/or the like.

The pulse generator 102, 104 can include a pulse control 304. In someembodiments, the pulse control 304 can be configured to control thegeneration of one or several pulses by the pulse generator 102, 104. Insome embodiments, for example, this information can identify one orseveral pulse patterns, programs, or the like. This information canfurther specify, for example, the frequency of pulses generated by thepulse generator 102, 104, the duration of pulses generated by the pulsegenerator 102, 104, the strength and/or magnitude of pulses generated bythe pulse generator 102, 104, or any other details relating to thecreation of one or several pulses by the pulse generator 102, 104. Insome embodiments, this information can specify aspects of a pulsepattern and/or pulse program, such as, for example, the duration of thepulse pattern and/or pulse program, and/or the like. In someembodiments, information relating to and/or for controlling the pulsegeneration of the pulse generator 102, 104 can be stored within thememory.

The pulse generator 102, 104 can include a charging module 306. In someembodiments, the charging module 306 can be configured to control and/ormonitor the charging/recharging of the pulse generator 102, 104. In someembodiments, for example, the charging module 306 can include one orseveral features configured to receive energy for recharging the pulsegenerator 102, 104 such as, for example, one or several inductivecoils/features that can interact with one or several inductivecoils/features of the charger 116 to create an inductive coupling tothereby recharge the pulse generator 102, 104.

In some embodiments, the charging module 306 can include hardware and/orsoftware configured to monitor the charging of the pulse generator 102,104. In some embodiments, the hardware can include, for example, acharging coil configured to magnetically couple with a charging coil ofthe charger 116. In some embodiments, these features can be configuredto monitor the temperature of one or several components of the pulsegenerator 102, 104, the rate of charge of the pulse generator 102, 104,the charge state of the pulse generator 102, 104, or the like. Thesefeatures can include, for example, one or several resistors,thermistors, thermocouples, temperature sensors, current sensors, chargesensors, or the like. In some embodiments, the charging module 306 canbe configured to monitor, for example, voltage of the energy storagefeatures, current flowing through, for example, a shunt circuitconfigured to channel excess current, one or several temperatures of,for example, the energy storage features and/or of the pulse generator102, 104, the presence of a detectable charge field, the charge state ofthe energy storage features, and/or the like. In some embodiments, theone or several parameters can be provided to the network interface 300,and communicated via network 114 to other components of the implantableneurostimulation system 100.

The pulse generator 102, 104 can include an energy storage device 308.The energy storage device 308, which can include the energy storagefeatures, can be any device configured to store energy and can include,for example, one or several batteries, capacitors, fuel cells, or thelike. In some embodiments, the energy storage device 308 can beconfigured to receive charging energy from the charging module 306.

With reference now to FIG. 4, a schematic illustration of one embodimentof the charger 116 is shown. In some embodiments, each of the componentsof the architecture of the charger 116 can be implemented using theprocessor, memory, and/or other hardware component of the charger 116.In some embodiments, the components of the architecture of the charger116 can include software that interacts with the hardware of the charger116 to achieve a desired outcome.

In some embodiments, the charger 116 can include, for example, a networkinterface 350, or alternatively, a communication module. The networkinterface 350, or alternatively, a communication module, can beconfigured to access the network 110 to allow communication between thecharger 116 and the other components of the implantable neurostimulationsystem 100. In some embodiments, the network interface 350, oralternatively, a communication module, can include one or severalantennas and software configured to control the one or several antennasto send information to and receive information from one or several ofthe other components of the implantable neurostimulation system 100.

In some embodiments, the charger 116 can include an indicator controlmodule 352. In some embodiments, the indicator control module 352 can beconfigured to receive data relating to one or several parametersmeasured at the implantable pulse generator 104. The indicator controlmodule 352 can use this information to determine whether charging wouldbe improved by repositioning and/or reorienting of the charger 116 withrespect to the implantable pulse generator 104. In some embodiments,this determination can include determining the relative effectiveness ofthe charging at a second, current position as compared to a first,previous position, and controlling the indicator to indicate increasedcharging effectiveness if the charging is more effective at the secondposition than and the first position, or similarly controlling theindicator to indicate the decreased charging effectiveness if thecharging is less effective at the second position than at the firstposition. In some embodiments, this can include comparing the datareceived from the implantable pulse generator 104 to stored data todetermine whether the charging effectiveness of the current position ofthe charger 116 is sufficient or insufficient. In the event that thecharging effectiveness is insufficient, then the indicator controlmodule 352 can be configured to control the indicator to indicate thisinsufficiency of the charging effectiveness. Similarly, in the eventthat the charging effectiveness is sufficient, then the indicatorcontrol module 352 can be configured to control the indicator toindicate this sufficiency of the charging effectiveness.

The charger 116 can include a charging module 354. The charging module354 can be configured to control and/or monitor the charging of one orseveral of the pulse generators 102, 104. In some embodiments, forexample, the charging module 354 can include one or several protocolsthat can request information from the one or several pulse generators102, 104 at one or several times before, during, and after charging.This information can be received by the charger 116 from the pulsegenerator 102, 104 and can be used to control the generation of and/orproperties of the charge field. In some embodiments, the charging module354 can include one or several features configured to transmit energycharging coils that can magnetically couple with the charging coil ofthe pulse generator 102, 104 to thereby recharge the pulse generator102, 104.

In some embodiments, the charging module 354 can be configured to powerthe charging coil of the charger 116 at any desired power level across acontinuous power spectrum, and in some embodiments, the charging module354 can be configured to power the charging coil of the charger 116 atone of several discrete power levels across a digitized power spectrum.In one such embodiment, for example, the charging module can beconfigured to power the charging coil of the charger 116 at one of 3, 4,5, 6, 7, 8, 9, 10, 15, 20, 30, 50, 100, or any other or intermediatediscrete power levels.

With reference now to FIG. 5, a perspective view of one embodiment ofthe implantable pulse generator 104 and the charger 116 is shown. Thecharger 116 includes an elongate body 140. The elongate body 140 can beconfigured to be placed against the body of the patient such as, forexample, directly against the skin of the patient, and/or proximate tothe skin of the patient such as, for example, against a piece ofclothing or apparel worn by the patient.

In some embodiments, the charger 116 can include at least one retentionfeature 142 that can be configured to hold the elongate body 140 in adesired position against the patient's body. In some embodiments, theretention feature 142 can be, for example, a strap, a band, or the like.In one such embodiment, for example, in which the charger 116 is placedon a portion of the body, such as, for example, the neck, torso, orlimb, including, one of a leg, a foot, an arm, and a hand, the retentionfeature 142 can secure the charger 116 to that portion of the body andcan secure the position and orientation of the charger 116 with respectto that portion of the body. In some embodiments, the retention feature142 can be configured to hold the elongate body 140 of the charger 116in a constant orientation with respect to the body of the patient. Insome embodiments, a constant orientation may include some variations ofthe orientation of the elongate body 140 described by an angle measuredfrom a longitudinal axis of the elongate body 140 in a first position tothe longitudinal axis of the elongate body 140 in a second position. Insome embodiments, this angle can be, for example, 1 degree, 5 degrees,10 degrees, 15 degrees, 20 degrees, 30 degrees, 40 degrees, or any otheror intermediate angle.

The charger 116 can include a charge head 144. The charge head 144 caninclude one or several features to facilitate the charging of theimplantable pulse generator 104. In some embodiments, these features caninclude, for example, the charge head charging coil that will bediscussed at greater length below.

As seen in FIG. 5, the charge head 144 includes a rotatable mount 146.In some embodiments, the rotatable mount 146 can be connected to thecharging coil of the charge head 144 and can be configured to allow therotation of the charging coil. The rotatable mount can include one orseveral features that can facilitate the rotation/re-orientation of therotatable mount. These can include, for example, a feature configured toengage with, for example, a key, a screwdriver, a wrench, or the like,one or several features configured to facilitate digital manipulationsuch as, for example, one or several knurls, grips, or the like, or anyother feature. In some embodiments, for example, the rotatable mount 146can be configured to allow the manipulation of the angular position ofthe charge head charging coil with respect to, for example, thelongitudinal axis of the elongate member 140.

As further seen in FIG. 5, the implantable pulse generator 104 can bepositioned with respect to the charger 116 to allow recharging of theimplantable pulse generator 104. In some embodiments, the implantablepulse generator 104 can be positioned so as to be within an effectivedistance or range from the charger 116. In some embodiments, thisdistance can be such that recharging of the implantable pulse generator104 is effective, and the distance can be, for example, within 10 cm ofthe charge head 144, 5 cm of the charge head 144, 4 cm of the chargehead 144, 3 cm of the charge head 144, 2 cm of the charge head 144, 1 cmof the charge head 144, 0.5 cm of the charge head 144, 0.1 cm of thecharge head 144, and/or any other or intermediate distance from thecharge head 144. In some embodiments, the implantable pulse generator104 can be positioned such that the implantable pulse generator 104 isdirectly below the charge head 144 of the charger 116. This positioningis indicated in FIG. 5 by axis 150. Alternatively, in some embodiments,implantable pulse generator 104 can be positioned so as to not bedirectly below the charge head 144 of charger 116.

With reference now to FIG. 6, a perspective view of one embodiment of areceiving coil 250, which can be any charging coil including, forexample, a charging coil that transmits or receives energy, that can beused in the implantable pulse generator 104 is shown. The receiving coil250 can comprise a variety of shapes and sizes and can be made of avariety of materials. The charging coil can comprise a solenoid. In someembodiments, the receiving coil 250 can be sized and shaped so as to fitwithin the implantable pulse generator 104, and specifically inside of ahousing of the implantable pulse generator 104. In one embodiment, forexample, the charging coil can be positioned proximate to a surface ofthe housing such that no other components of the implantable pulsegenerator 104 are between the receiving coil 250 and this surface. Insome embodiments, the implantable pulse generator 104 can be implantedsuch that this surface is proximate to the skin of the patient and/orrelatively more proximate to the skin of the patient than other portionsof the implantable pulse generator.

In some embodiments, the receiving coil 250 can be configured tomagnetically couple with features of the charger 116 such as, forexample, a charging coil of the charger 116 to recharge the one orseveral energy storage features of the implantable pulse generator 104.

In some embodiments, and to facilitate the magnetic coupling of thereceiving coil 250 with the charging coil of the charger 116, thereceiving coil 250 of the implantable pulse generator 104 can have ahigh Q factor. In some embodiments, a high Q factor can have a Q valueof at least 10, 20, 30, 40, 50, 75, 100, 150, 200, 300 and/or any otheror intermediate value. In some embodiments, for example, the Q factor ofthe receiving coil 250 can be, for example, at least 10, at least 20, atleast 30, at least 40, at least 50, at least 60, at least 70, at least80, at least 100, at least 120, at least 200, and/or any other orintermediate value.

The receiving coil 250 can include a core 252. The core 252 can comprisea variety of shapes and sizes and can be made from a variety ofmaterials. In some embodiments, the core 252 can be sized and shaped tofacilitate the wrapping of one or several wires around the core 252and/or the core 252 can be sized and shaped to achieve and/or facilitatein achieving a desired Q factor for the receiving coil 250. In someembodiments, the core 252 can comprise a ferritic core, and in someembodiments, the core 252 can comprise a soft ferritic core.

In some embodiments, and as shown in FIG. 6, the core 252 can comprisean elongate member, and can specifically comprise an elongatecylindrical member that can have, a distal, first end 254 and aproximal, second end 256. As seem in FIG. 6, an axis 255, which can be alongitudinal axis, can extend along the centerline of the core 252between the first end 254 and the second end 256, and the length of thecore 252 can be measured and/or defined with respect to this axis 255.In some embodiments, the length of the core 252 can be, for example,approximately 0.1 inches, 0.2 inches, 0.3 inches, 0.4 inches, 0.5inches, 0.6 inches, 0.7 inches, 0.8 inches, 0.9 inches, 1 inch, 1.5inches, 2 inches, 5 inches, and/or any other or intermediate length. Insome embodiments, the core can have a radius, measured from the axis 255of approximately 0.01 inches, 0.02 inches, 0.03 inches, 0.04 inches,0.05 inches, 0.06 inches, 0.07 inches, 0.08 inches, 0.09 inches, 0.098inches, 0.1 inches, 0.15 inches, 0.2 inches, 0.5 inches, and/or anyother or intermediate radius.

The receiving coil 250 can further include a plurality of windings 258around the core 252. The windings 258 can, together with the core 252,allow receiving coil 250 to magnetically couple with charger 116 torecharge the energy storage features of the implantable pulse generator104. In some embodiments, the windings 258 can be made by looping wire260, which wire 260 can be any type of wire including, for example, alitz wire, and which can be any material having desired properties, andspecifically can be a metal wire, one or more times around core 252. Insome embodiments, the windings 258 can comprise any desired number ofloops of wire, and can, for example, comprise 2 loops, 5 loops, 10loops, 15 loops, 20 loops, 25 loops, 29 loops, 30 loops, 35 loops, 40loops, 50 loops 100 loops, 200 loops, 1,000 loops, and/or any other orintermediate number of loops.

In some embodiments, and as depicted in FIG. 6, the wire 260 can belooped around core 252 so as to create a plurality of layers of loops atdifferent radial distances from axis 255. As specifically depicted inFIG. 6, a first layer of loops 257 is positioned so as to contact core252 and to be a first radial distance from axis 255, and a second layerof loops 259 is positioned so as to contact the first layer of loops 257and be a second radial distance from axis 255. In some embodiments, thefirst layer of loops 257 can comprise 1 loop, 2 loops, 5 loops, 10loops, 12 loops, 13 loops, 15 loops, 16 loops, 18 loops, 20 loops, 30loops, 50 loops, 100 loops, and/or any other or intermediate number ofloops, and the second layer of loops 259 can comprise 1 loop, 2 loops, 5loops, 10 loops, 12 loops, 13 loops, 15 loops, 16 loops, 18 loops, 20loops, 30 loops, 50 loops, 100 loops, and/or any other or intermediatenumber of loops. In the embodiment depicted in FIG. 6, the first radialdistance is less than the second radial distance, and thus the radius ofthe loops of the first layer of loops 257 is less than the radius of theloops of the second layer of loops 259.

The receiving coil 250 can include a capacitor 262. The capacitor 262can comprise a variety of shapes and sizes and can have a variety ofelectrical properties. In some embodiments, for example, the capacitor262 can comprise a high Q capacitor and in some embodiments, can be ahigh Q COG capacitor.

The capacitor 262 can, in connection with windings 258, create a tankcircuit. In some embodiments, this tank circuit can be a high Q tankcircuit. In some embodiments, the high Q tank circuit can have a Q valueof at least 10, 20, 30, 40, 50, 75, 100, 150, 200, 300, and/or any otheror intermediate value. The tank circuit can increase the Q factor of thereceiving coil 250. This Q factor of the receiving coil 250 increases asthe distance between the windings 258 and the capacitor 262 decreases.Thus, in some embodiments, the capacitor can, and as shown in FIG. 6, beplaced on the windings 258, and in some embodiments, the capacitor 262can be placed in proximity to the windings 258 such as, for example, adistance of less than 5 cm from the windings 258, less than 4 cm fromthe windings 258, less than 3 cm from the windings 258, less than 2 cmfrom the windings 258, less than 1 cm from the windings 258, less than0.5 cm from the windings 258, less than 0.1 cm from the windings 258,and/or any other or intermediate distance from the windings 258.

The receiving coil 250 can include a first lead 264 and a second lead266. The first and second leads 264, 266 can be used to electricallyconnect the receiving coil 250 to other features and/or components ofthe implantable pulse generator 104. In some embodiments, the leads 264,266 can extend from the capacitor 262, and in some embodiments, theleads 264, 266 can extend from the windings 258.

With reference now to FIG. 7, a perspective view of one embodiment of atransmitting coil 350 that can be used in a charger is shown. Thetransmitting coil 350 can be any charging coil, including, for example,a charging coil that transmits or receives energy. The transmitting coil350 can comprise a variety of shapes and sizes and can be made of avariety of materials. In some embodiments, the transmitting coil 350 cancomprise a solenoid. In some embodiments, the transmitting coil 350 canbe sized and shaped so as to fit within the charger 116, andspecifically within the charge head 144 of the charger 116. In someembodiments, the transmitting coil 350 can be configured to magneticallycouple with features of the implantable pulse generator 104 such as, forexample, the receiving coil 250 of the implantable pulse generator 104to recharge the one or several energy storage features of theimplantable pulse generator 104.

In some embodiments, and to facilitate the magnetic coupling of thetransmitting coil 350 with the receiving coil 250, the transmitting coil350 can have a high Q factor. In some embodiments, for example, the Qfactor of the transmitting coil 350 can be, for example, at least 50, atleast 100, at least 150, at least 200, at least 250, at least 250, atleast 350, at least 350, at least 450, at least 500, at least 1,000,and/or any other or intermediate value. In some embodiments, the Q valueof the transmitting coil 350 can be any value that is larger than the Qvalue of the Q value of the receiving coil 250. In some embodiments, theQ value of the transmitting coil 350 can be, for example, 25, 50, 75,100, 120, 150, 200, 220, 250, 300, 400, 500, 1,000, or any other orintermediate value larger than the Q value of the receiving coil 250.

The transmitting coil 350 can include a core 352. The core 352 cancomprise a variety of shapes and sizes and can be made from a variety ofmaterials. In some embodiments, the core 352 can be sized and shaped tofacilitate the wrapping of one or several wires around the core 352and/or the core 352 can be sized and shaped to achieve and/or facilitatein achieving a desired Q factor for the transmitting coil 350. In someembodiments, the core 352 can comprise a metal core and/or a ferriticcore, and in some embodiments, the core 352 can comprise a soft ferriticcore.

In some embodiments, and as shown in FIG. 7, the core 352 can comprisean elongate member, and can specifically comprise an elongaterectangular member that can have first end 354 and a second end 356. Asseem in FIG. 7, an axis 357, which can be a longitudinal axis, canextend along the centerline of the core 352 between the first end 354and the second end 356, and the length of the core 352 can be measuredand/or defined with respect to this axis 357.

The core 352 can comprise a first foot 358 and/or a second foot 360. Insome embodiments, the first foot 358 can be located at and/or proximateto the first end 354 and the second foot 360 can be located at and/orproximate to the second end 356. In some embodiments, the first andsecond feet 358, 360 extend away from the axis 357, and in someembodiments, the first and second feet 358, 360 extend in the samedirection and to the same extent away from the axis 357. In someembodiments, the first and second feet 358, 360 can be configured forsliding engagement with other components of the charger 116, andspecifically with other components of the charge head 144. The first andsecond feet 358, 360 can, in some embodiments, be made of the samematerial as the core 352, and in some embodiments, the feet 358, 360 canbe made of a different material than the core 352.

In some embodiments, the extension of the feet 358, 360 away from theaxis 357 of the core 352 can facilitate in guiding and shortening themagnetic field, which corresponds to the charging field, generated bythe transmitting coil 350. In some embodiments, this can increase thedirectionality of the magnetic field and can increase the couplingcoefficient between the charger 116 and the implantable pulse generator104.

The transmitting coil 350 can further include a plurality of windings362 around the core 352. The windings 362 can, together with the core352 allow transmitting coil 350 to magnetically couple with implantablepulse generator 104 to recharge the energy storage features of theimplantable pulse generator 104. In some embodiments, the windings 362can be made by looping wire 364, which wire 364 can be any type of wireincluding, for example, a litz wire, and which can be any materialhaving desired properties, and specifically can be a metal wire, one ormore times around core 352. In some embodiments, the windings 362 cancomprise any desired number of loops of wire, and can, for example,comprise 2 loops, 5 loops, 10 loops, 15 loops, 20 loops, 25 loops, 29loops, 30 loops, 35 loops, 40 loops, 50 loops 100 loops, 200 loops,1,000 loops, and/or any other or intermediate number of loops. In someembodiments, the windings 362 can be exposed, and in some embodiments,the windings 362 can be covered by, for example, tape such as a mylartape.

In some embodiments, although not depicted in FIG. 7, the wire 364 canbe looped around core 352 so as to create a plurality of layers of loopsat different radial distances from axis 357. Specifically a first layerof loops can be positioned so as to contact core 352 and to be a firstradial distance from axis 357, and a second layer of loops can bepositioned so as to contact the first layer of loops and be a secondradial distance from axis 357. In such an embodiment, the first radialdistance can be less than the second radial distance, and thus thevolume encompassed by the loops of the first layer of loops can be lessthan the volume encompassed by the loops of the second layer of loops.

The transmitting coil 350 can include a first lead 366 and a second lead368. The first and second leads 366, 368 can be used to electricallyconnect the transmitting coil 350 to other features and/or components ofthe charger 116. In some embodiments, the leads 366, 368 can be the endsof wire 364, and in some embodiments, the leads 366, 368 can beconnected to the ends of wire 364.

With reference now to FIG. 8, a section view of one embodiment of theimplantable pulse generator 104 and the charger 116 is shown. Thesection view is taken along the plane extending through A-A and B-Bindicated in FIG. 2.

As seen in FIG. 5, the implantable pulse generator 104 includes ahousing 802 that is sized, shaped, and configured to hold components ofthe implantable pulse generator 104 including, for example, thereceiving coil 250. As depicted in FIG. 8, the receiving coil 250includes the core 252 having the first end 254, the second end 256, andthe axis 255 extending therebetween. The axis 255 shown in FIG. 8 isparallel with the plane of FIG. 8. The receiving coil 250 shown in FIG.8 further includes windings 258 comprising loops of wire 260.

In some embodiments, the implantable pulse generator 104 can includecircuitry 803. The circuitry 803 can include the processor, the energystorage features, one or several communication features, and the like.In some embodiments, this circuitry can be configured, to control theoperation of the implantable pulse generator 104.

FIG. 8 further includes the charger 116, and specifically, the chargehead 144 of the charger 116. The charger 116 includes a housing 804 thatis sized, shaped, and configured to hold components of the charger 116including, for example, the transmitting coil 350 and the rotatablemount 146. The housing 804 includes a base 806 that can be configuredfor placement adjacent to and/or on the patient's body, including on thepatient's skin 801. In some embodiments, the base 806 can comprise aplanar and/or substantially planar portion, referred to herein as acontact surface, that can be placed adjacent to and/or on the patient'sbody.

The housing 804 can further include a lock feature 808 that can securethe rotatable mount 146 in a desired position. The lock feature 808 cancomprise a variety of shapes and sizes, and can be any desired featureor mechanism that can secure the rotatable mount in one or severaldesired locations. In some embodiments, the lock feature 808 cancomprise one or several set-screws, latches, detents, or the like.

The rotatable mount 146 can be connected to the transmitting coil 350.In some embodiments, the connection of the rotatable mount 146 to thetransmitting coil 350 can enable the changing of the orientation of thetransmitting coil 350 with respect to the orientation of thelongitudinal axis of the elongate member 140 by the rotation of therotatable mount 146. In some embodiments, the rotatable mount 146 can berotatable in one or two directions up to 20 degrees, up to 30 degrees,up to 45 degrees, up to 60 degrees, up to 90 degrees, up to 120 degrees,up to 180 degrees, up to 360 degrees, and/or any other or intermediateamount of rotation.

As shown in FIG. 8, the transmitting coil 350 can include the first andsecond ends 354, 356 and the axis 357 extending therebetween. The axis357 shown in FIG. 8 is parallel with the plane containing FIG. 8.

The transmitting coil 350 can further include windings 362 comprisingloops of wire 364. The transmitting coil 350 shown in FIG. 8 includesthe first and second feet 358, 360 that extend from the axis 357 and arepositioned within a track 810. In some embodiments, the track 810 can belocated within a portion of the housing 804 and/or attached to thehousing 804. The track 810 can be configured to receive the first andsecond feet 358, 360 and to facilitate in guiding the rotation of thetransmitting coil 350 when the rotatable mount, and the therewithconnected transmitting coil 350 is rotated. In some embodiments, thetrack 810 can be configured to allow rotations of the transmitting coil350 in one or two directions up to 20 degrees, up to 30 degrees, up to45 degrees, up to 60 degrees, up to 90 degrees, up to 120 degrees, up to180 degrees, up to 360 degrees, and/or any other or intermediate amountof rotation.

The charger 116 can include circuitry 812. The circuitry 812 can includethe processor, one or several communication features, and the like. Insome embodiments, the circuitry 812 can be configured to receive one orseveral communications from the implantable pulse generator 104 and useinformation in these signals to detect the angular position of thereceiving coil 250 with respect to the transmitting coil 350 of thecharging head 146. In some embodiments, the detection of the angularposition of the receiving coil 250 with respect to the transmitting coil350 can include retrieving data relating to the power level of thecharger, the effectiveness of the charging field at the implantabledevice 104, and data relating to changes in the effectiveness of thecharging field at the implantable device 104 when the charger 116 isbeing moved relative to the implantable pulse generator 104, including,for example, when the angle between the receiving coil 250 and thetransmitting coil 350 is changing. The angle between the receiving coil250 and the charging coil 350 can then be determined based on thisretrieved information. In some embodiments, this retrieved informationcan alternatively be used to look up one or more values stored within adatabase, which values can identify one or several potential anglesbetween the receiving coil 250 and the charging coil 350. In someembodiments, this circuitry 812 can be configured, to control theoperation of the charger 116.

As seen in FIG. 8, the axes 255, 357 are non-coaxial with each other. Incontrast to better efficiency that results from the axial alignment ofcommon implantable devices, the non-axial alignment of axes 255, 357adversely affects the ability of the charging coils 250, 350 tomagnetically couple. This ability to magnetically couple is furtherdegraded to the extent that the axes 255, 357 of the charging coils 250,350 are non-parallel. Thus, rotatable mount 146 can allow a user tore-orient the axes 255, 357 so that they are closer to parallel, andthereby improve the efficiency of the magnetic coupling between thecharging coils 250, 350. Specifically, the embodiment shown in FIG. 8allows the rotation of the transmitting coil 350 so that the axes 255,357 of charging coils 250, 350 are parallel, or relatively moreparallel.

With reference now to FIG. 8, a flowchart illustrating one embodiment ofa process 500 for providing an alignment indicator for a charger 116 isshown. The process 500 can be performed by one or several of thecomponents of the implantable neurostimulation system 100, and in someembodiments, can be performed by the charger 116. In some embodiments,the process 500 can be performed by some or all of the components of thecharger 116 including, for example, the network interface 350, theindicator control module 352, and/or the charging module 354. Theprocess 500 can be performed as part of recharging, and can bespecifically performed to facilitate in the positioning and/or orientingof the charger 116 with respect to the implantable pulse generator 104.The process 500 can facilitate in positioning and/or orienting of thecharger 116 through the control of one or several indicators which canprovide information to the user regarding the effectiveness of acharging field at the implantable pulse generator 104, whicheffectiveness can vary, at least in part, based on the positioningand/or orienting of the charger 116 with respect to the implantablepulse generator 104.

The process 500 begins at block 502 wherein the charging coil of thecharger 116 is operated at a first power level. In some embodiments,this first power level can describe the power of the charging fieldgenerated by the charging coil of the charger 116. This first powerlevel can be obtained by controlling, for example, one or both of thevoltage of the charging coil of the charger 116 and the current of thecharging coil of the charger 116. In some embodiments, this first powerlevel can be a zero power level, in which no charging field isgenerated, and in some embodiments, this first power level can be anon-zero power level, in which a charging field is generated. In someembodiments, the charging coil can be operated at the first level basedon controls received from, for example, the charging module 354 of thecharger 116.

After the charging coil is set to the first level, the process 500proceeds to block 504, wherein a signal is received from a chargeddevice. In some embodiments, the signal can be received via the networkinterface 350 of the charger 116. The signal can be received from thecharged device, which can be the implantable pulse generator 104 vianetwork 110, and specifically, can be received from the networkinterface 300 of the implantable pulse generator 104. In someembodiments, the signal can be analyzed by the processor of the charger116. In some embodiments, the signal can be received at a discrete time,and in some embodiments, the signal can be repeatedly and/orcontinuously received during the performing of steps 506-514. In somesuch embodiments, process 500 can become a dynamic process in that manyof steps 506-514 are simultaneously performed as the signal isrepeatedly and/or continuously received.

The signal can include information relating to a parameter of theimplantable pulse generator 104, and specifically to a parameteridentifying the effect of the charging field on the implantable pulsegenerator 104. This parameter can, for example, identify the voltageinduced by the charging field at the charging coil of the implantablepulse generator 104, identify the current induced by the charging fieldat the charging coil of the implantable pulse generator 104, identify atemperature of the implantable pulse generator 104, of a component ofthe implantable pulse generator 104, or of surrounding tissue, identifya charge state of the energy storage features of the implantable pulsegenerator 104, or the like.

After the signal received from the charged device has been received, theprocess 500 proceeds to block 506, wherein the signal is compared to oneor several charging criteria. In some embodiments, these criteria canrelate to whether and to what degree the charging field is charging theenergy storage feature of the implantable pulse generator 104. Thesecriteria can relate to, for example, whether the charging field isdetectable at the implantable pulse generator 104, the voltage inducedby the charging field in the charging coil of the implantable pulsegenerator 104, the current induced by the charging field in the chargingcoil of the implantable pulse generator 104, the charge state of theenergy storage features of the implantable pulse generator 104, thetemperature of the implantable pulse generator 104 or componentsthereof, or the like. In some embodiments, the comparison of the signalto the criteria can include a determination of whether the chargingfield allows safe charging of the implantable pulse generator 104 andthe degree to which the charging field allows effective charging of theimplantable pulse generator 104 such as, for example, whether themeasured parameter (induced voltage, induced current, temperature, tempdelta, etc. . . . falls within an acceptable range).

After the signal has been compared to the charging criteria, the process500 proceeds to decision state 508, wherein it is determined if thecharge coil level should be adjusted. In some embodiments, this caninclude, for example, increasing the level of the charging field if thecharging field strength is inadequate, decreasing the level of thecharging field if the charging field strength is too high, or the like.In some embodiments, this can further include determining thatadjustment to the position and/or orientation of the charger 116 withrespect to the implantable pulse generator 104 is desirable to increasethe effectiveness of the charging field.

If it is determined that the coil level is to be adjusted, then theprocess 500 proceeds to block 510, wherein the coil level is adjusted.In some embodiments, this can include, for example, incrementing ordecrementing the coil level to the next one of several discrete levels,or increasing the coil level by a predetermined value.

Returning again to decision state 508, if it is determined that the coillevel should not be adjusted, then the process 500 proceeds to block512, wherein the indicator, which can be an alignment indicator isactivated. In some embodiments, in which the signal is repeatedly and/orcontinuously received, the indicator can be controlled to reflect thechange of charging field effectiveness as represented by the signal overa period of time. Thus, in such an embodiment, if the effectiveness ofthe charging field increases, which can be due to, for example, therepositioning and/or reorienting of the charger 116, the indicator canbe controlled to reflect this increased effectiveness. Similarly, if theeffectiveness of the charging field decreases, which can be due to, forexample, the repositioning and/or reorienting of the charger 116, theindicator can be controlled to reflect this decreased effectiveness.

With reference now to FIG. 9, a flowchart illustrating one embodiment ofa process 600 for providing an alignment indicator for a charger basedon detected variations in measured voltage and current is shown. Theprocess 600 can be performed by one or several of the components of theimplantable neurostimulation system 100, and in some embodiments, can beperformed by the charger 116. In some embodiments, the process 600 canbe performed by some or all of the components of the charger 116including, for example, the network interface 350, the indicator controlmodule 352, and/or the charging module 354. The process 600 can beperformed as part of recharging, and can be specifically performed tofacilitate in the positioning of the charger 116 with respect to theimplantable pulse generator 104. The process 600 can facilitate inpositioning of the charger 116 through the control of one or severalindicators which can provide information to the user regarding theeffectiveness of a charging field at the implantable pulse generator104, which effectiveness can vary, at least in part, based on thepositioning of the charger 116 with respect to the implantable pulsegenerator 104.

The process 600 begins at block 602 wherein the charger 116 is powered.In some embodiments, the powering of the charger 116 can correspond to auser turning the charger 116 on, or to selecting a charging mode ofoperation. After the charger is powered, the process 600 proceeds toblock 604, wherein the charging coil is set to and/or operated at aninitial level. In some embodiments, this initial level can describe thepower of the charging field generated by the charging coil of thecharger 116. This initial level can be obtained by controlling, forexample, one or both of the voltage of the charging coil of the charger116 and the current of the charging coil of the charger 116. In someembodiments, this initial level can be a zero power level, in which nocharging field is generated, and in some embodiments, this initial levelcan be a non-zero power level, in which a charging field is generated.In some embodiments, the charging coil can be operated at the initiallevel based on controls received from, for example, the charging module354 of the charger 116.

After the charging coil is set to an initial level, the process 600proceeds to block 606, wherein communication between the implantablepulse generator 104 and the charger 116 is established. In someembodiments, this can include, for example, the charger 116 initiatingcommunication by sending a query to the implantable pulse generator 104,and the implantable pulse generator 104 responding to the query of thecharger 116.

After communication between the implantable pulse generator 104 and thecharger 116 has been established, process 600 proceeds to decision state608, wherein the communication link between the implantable pulsegenerator 104 and the charger is confirmed. If it is determined thatcommunication has not been established, then the process 600 proceeds toblock 610, wherein the event is logged in, for example, the memory ofthe charger, and the process 600 then proceeds to block 612, wherein thefailure is indicated. In some embodiments, this indication can identifya specific failure, in this case, for example, a failure to establishcommunication between the implantable pulse generator 104 and thecharger 116 is indicated, and in some embodiments, the indication of thefailure can be generic.

Returning again to decision state 608, if it is determined thatcommunication has been established, then the process 600 proceeds toblock 614, wherein the indicators are activated. In some embodiments,this can include powering the indicators. After the indicators have beenactivated, the process 600 proceeds to block 616 wherein the coil levelof the charging coil of the charger 116 is increased. After the coillevel of the charging coil of the charger 116 has been increased, theprocess 600 proceeds to decision state 618, wherein it is determined ifthe charging coil is operating at its maximum level, and specifically ifa preset upper limit has been reached. This determination can be made byidentifying the present level of the charging coil and comparing thepresent level of the charging coil to the maximum possible level of thecharging coil. If the present level of the charging coil is less thanthe maximum level of the charging coil, then the charging coil is notoperating at its maximum level. Alternatively, if the present level ofthe charging coil is equal to the maximum level, then the charging coilis operating at the maximum level.

If it is determined that the charging coil is not operating at itsmaximum level, then the process 600 proceeds to decision state 620,wherein it is determined if the charging field is detected at thecharged device, and specifically, if the charging field is detectable atthe implantable pulse generator 104. In some embodiments, thisdetermination can be made based on information that can be received, viaa signal or via a communication from the implantable pulse generator104. In some embodiments, this information can include data relating toone or several parameters, identifying the effect of the charging fieldon the implantable pulse generator 104. If it is determined, based onthis data, that the charging field is not detectable at the chargeddevice, then the process 600 returns to block 616, and proceeds asoutlined above.

If it is determined that the charging field is detected at the chargeddevice, then the process 600 proceeds to decision state 622, wherein itis determined if the charging field, as measured at the implantablepulse generator, is too strong, or alternatively, if the charging fieldis at an acceptable strength level. In some embodiments, an acceptablestrength level can be a level at which the implantable pulse generatoris capable of recharging the energy storage features. In someembodiments, this can be determined by comparing a current property ofthe energy storage features, such as, for example, the voltage of theenergy storage features with a parameter of the charging field, such as,for example, the voltage induced by the charging field at the chargingcoil of the implantable pulse generator 104. In some embodiments, anacceptable strength level can be a level at which the implantable pulsegenerator is capable or recharging the energy storage features and anacceptable rate or within an acceptable time range.

In some embodiments, the acceptability of the strength level of thecharging field can be determined by determining whether the chargingfield is causing excessive heating of the implantable pulse generator104 or one or several components thereof, or if the strength of thecharging field is resulting in the induction of undesirable currentlevels at the charging coil of the implantable pulse generator 104. Inone embodiment, for example, this can be determined by measuring thecurrent passing through the shunt circuit. In some embodiments, theshunt circuit can be any circuit that can dispose of or channel excesscurrent generated by the charging field. If this current exceeds athreshold value, then the strength of the charging field may be toohigh. Similarly, if the temperature of the implantable pulse generator,or one or several components thereof exceeds a threshold temperature,then the strength of the charging field may be too high.

If it is determined that the charging field is too strong, then theprocess 600 proceeds to block 624, wherein the coil level is decreased.After the coil level has been decreased, the process 600 returns todecision state 622 and proceeds as outlined above.

Returning again to decision state 618, if it is determined that thecharging coil has reached its maximum level, or returning again todecision state 622, if it is determined that the charging field is nottoo strong, then process 600 proceeds to decision state 626, wherein itis determined if the charging field is detected at the charged device,and specifically, if the charging field is detectable at the implantablepulse generator 104. In some embodiments, this decision state canreplicate the determination of decision state 620. In such anembodiment, this determination can be made based on information that canbe received, via a signal or via a communication from the implantablepulse generator 104. In some embodiments, this information can includedata relating to one or several parameters, identifying the effect ofthe charging field on the implantable pulse generator 104. If it isdetermined, based on this data, that the charging field is not detected,then the process 600 proceeds to block 610 wherein the event is loggedin, for example, the memory of the charger, and the process 600 thenproceeds to block 612, wherein the failure is indicated. In someembodiments, this indication can identify a specific failure, in thiscase, for example, a failure create a charging field detectable at theimplantable pulse generator 104 is indicated, and in some embodiments,the indication of the failure can be generic.

Returning again to decision state 626, if it is determined that thecharging field is detected, then the process 600 proceeds to decisionstate 628 wherein it is determined if there is a change in the voltageinduced by the charging field at the charging coil of the implantablepulse generator 104 The determination of decision state 628 can be basedon data contained in one or several signals received from theimplantable pulse generator 104 during the performance of the process600.

In some embodiments, decision state 628 can, in connection with decisionstate 630 be used to determine whether the effectiveness of the chargingfield at the charging coil of the implantable pulse generator 104 isincreasing or decreasing. In some embodiments, these changes to theeffectiveness of the charge coil can be caused by the movement and/orrepositioning and/or reorienting of the charger 116 with respect to theimplantable pulse generator 104. In some embodiments the advancement ofprocess 600 to decision state 628 can be delayed until a predeterminedtime interval has passed, and can be preceded by the activation of anindicator directing the user to reposition the charger 116. In such anembodiment, this can result in comparing the effectiveness of thecharging field at a first time to the effectiveness of the chargingfield at a second time. In some embodiments, this can result indetermining an effectiveness of the charging field at a first time basedon a first signal, and determining the effectiveness of the chargingfield at a second time based on a second signal. In some embodiments,this can be repeated until a desired and/or maximum effectiveness levelis identified, and in some embodiments, this can be repeated until apre-determined amount of time has passed.

If it is determined that there is no change in the voltage induced bythe charging field at the charging coil of the implantable pulsegenerator 104, then the process 600 proceeds to decisions state 630,wherein it is determined if there is a change in the current induced bythe charging field at the charging coil of the implantable pulsegenerator 104. In some embodiments, this change in current induced bythe charging field at the charging coil of the implantable pulsegenerator 104 can be based on data received at the charger 116 from theimplantable pulse generator 104, which data can identify, for example,changes to the current flowing through the shunt circuit of theimplantable pulse generator 104.

If it is determined that the current induced by the charging field atthe charging coil of the implantable pulse generator 104 is higher atdecisions state 630, as compared to the previous current induced by thecharging field at the charging coil of the implantable pulse generator,or if it is determined that the voltage induced by the charging field atthe charging coil of the implantable pulse generator 104 is higher atdecision state 628, as compared to the previous voltage induced by thecharging field at the charging coil of the implantable pulse generator,then the process 600 proceeds to block 632, wherein the indicators arecontrolled to indicate the increased voltage or current. In someembodiments, this can likewise indicate an increased effectiveness ofthe charging field at the charging coil of the implantable pulsegenerator 104.

Returning again to decision state 630, if it is determined that thecurrent induced by the charging field at the charging coil of theimplantable pulse generator 104 is lower at decisions state 530, ascompared to the previous current induced by the charging field at thecharging coil of the implantable pulse generator, or if it is determinedthat the voltage induced by the charging field at the charging coil ofthe implantable pulse generator 104 is lower at decision state 628, ascompared to the previous voltage induced by the charging field at thecharging coil of the implantable pulse generator, then the process 600proceeds to block 634, wherein the indicators are controlled to indicatethe decreased voltage or current. In some embodiments, this can likewiseindicate an decreased effectiveness of the charging field at thecharging coil of the implantable pulse generator 104.

After the indicators have been adjusted as in either block 632 or block634, or returning again to decision state 630, if it is determined thatthere has been no change in the current induced by the charging field,the process 600 proceeds to decision state 636, wherein it is determinedwhether to continue process 600. In some embodiments, this can include,for example, determining whether a predetermined amount of time haspassed, after which the process 600 should be terminated. In someembodiments, decision state 636 can include determining whether theeffectiveness of the charging field has reached a maximum value, orexceeded an effectiveness threshold. If it is determined that process600 should not be continued, then process 600 proceeds to block 638 andterminates. If it is determined that process 600 should continue,process 600 returns to decision state 628 and proceeds as outlinedabove. In some embodiments, the process 600 can be performed and/orrepeated at any desired rate. In some embodiments, for example, process600 can be performed and/or repeated 1,000 times per second, 500 timesper second, 200 times per second, 100 times per second, 50 times persecond, 25 times per second, 10 times per second, 5 times per second, 2times per second, 1 times per second, 30 times per minutes, 20 times perminute, 10 times per minute, 5 times per minute, 1 time per minute, 30times per hour, 20 times per hour, 10 times per hour, 5 times per hour,1 time per hour, and/or any other or intermediate rate.

With reference now to FIG. 10, a flowchart illustrating one embodimentof a process 700 in which movement of a charger is detected during thecharging is shown. In some embodiments, the process 700 can be performedduring the charging of the implantable pulse generator 104 to detectmovement of the charger 116 with respect to the implantable pulsegenerator 104. The process can be performed by the implantable pulsegenerator 104, the charger 116, and/or any other components of theimplantable neurostimulation system 100. The process 700 can beperformed during the charging of the implantable pulse generator 104. Insome embodiments, the process 700 can be continuously performed duringthe charging of the implantable pulse generator 104, and in someembodiments, the process 700 can be periodically performed during thecharging of the implantable pulse generator.

The process 700 begins at block 702, wherein charge data is received bythe charger 116 from a charged device, which can be, for example, theimplantable pulse generator 104. In some embodiments, this charge datacan include information identifying the charge state of the energystorage features of the implantable pulse generator 104, and in someembodiments, this information can identify whether the charging of theimplantable pulse generator 104 is complete. This information can bereceived by the network interface 350 of the implantable pulse generator104 from the network interface 300 of the implantable pulse generator104.

After the charge data has been received, the process 700 proceeds todecision state 704, wherein it is determined if the charging of theimplantable pulse generator 104 is complete. In some embodiments, thisdetermination can be made based on the charge data received in block702, which data can include information identifying the charge state ofthe energy storage features of the implantable pulse generator 104,and/or whether the charging of the implantable pulse generator 104 iscomplete. If it is determined that the charging is complete, thenprocess 700 proceeds to bock 706, wherein the charging coil of thecharger 116 is turned off.

Returning again to decision state 704, if it is determined that chargingis not complete, process 700 proceeds to decision state 708, whereintemperature data contained in the received charge data is evaluated todetermine if the temperature of the implantable pulse generator 104 orcomponent thereof is too high. In some embodiments, the temperature datacan identify the temperature of the implantable pulse generator 104and/or of one or several components of the implantable pulse generator104. The temperature data can be evaluated to determine whether thetemperature of the implantable pulse generator 104, or of one or severalcomponents thereof, is too high. In some embodiments, this can includedetermining if the temperature of the implantable pulse generator 104 orof one or several components thereof is higher than a threshold value,which threshold value can be stored in memory of the implantableneurostimulation system 100. In some embodiments, the process 700 can,in decision state 708, determine if the temperature of the implantablepulse generator 104 or a component thereof is above a first threshold,which can be indicative of a temperature that is too high, but is atdangerous levels.

If it is determined that the temperature is too high, then the process700 proceeds to decision state 710, wherein it is determined if thetemperature of the implantable pulse generator 104 or component thereofis an extreme temperature. This determination can be based ontemperature data received as part of the charge data in block 702.

In some embodiments, an extreme temperature can be a temperature at adangerous level. In some embodiments, the difference between atemperature that is too high and an extreme temperature can be found inhow each temperature is resolved. Thus, in some embodiments, atemperature that is too high may be resolved by decreasing the level ofthe charging field, whereas an extreme temperature is resolved bystopping charging.

If it is determined that the implantable pulse generator 104 orcomponent thereof has reached an extreme temperature, then the process700 proceeds to block 712, wherein the charging coil of the charger 116is turned off. If it is determined that the implantable pulse generator104 or component thereof has not reached an extreme temperature, thenthe process proceeds to decision state 714, wherein it is determined ifthe charging coil of the charger 116 is operating at its minimum level,which can be, for example, a preset lower limit. This determination canbe made by identifying the present level of the charging coil andcomparing the present level of the charging coil to the minimum possiblelevel of the charging coil. If the present level of the charging coil isgreater than the minimum level of the charging coil, then the chargingcoil is not operating at its minimum level. Alternatively, if thepresent level of the charging coil is equal to the minimum level, thenthe charging coil is operating at the minimum level.

If it is determined that the charging coil of the charger 116 isoperating at its minimum level, then the process 700 proceeds to block712, wherein the charging coil of the charger 116 is turned off. If itis determined that the charging coil of the charger 116 is not operatingat its minimum level, then the process 700 proceeds to decision state716, wherein it is determined if the implantable pulse generator 104 ischarging. In some embodiments, this determination can comprise a binarydetermination of whether charging is occurring or not, and in someembodiments, this determination can comprise a qualification of thedegree to which charging is occurring. In one specific embodiment,decision state 716 can include determining if charging is occurring andqualifying the degree to which charging is occurring. In thisembodiment, decision state 716 can further include estimating the degreeto which the coil level of the charging coil of the charger 116 can bedecreased without ending charging and/or the degree to which a decreasein the coil level of the charging coil of the charger will impact theeffectiveness of the charging field. If it is determined that theimplantable pulse generator 104 is not charging, then the process 700proceeds to block 712, wherein the charging coil of the charger 116 isturned off.

If it is determined that the implantable pulse generator 104 ischarging, then the process 700 proceeds to block 718, wherein the levelof the charging coil of the charger 116 is decreased. After the level ofthe charging coil of the charger 116 has been decreased, the process 700proceeds to block 712, wherein the charging coil of the charger 116 isturned off.

Returning again to decision state 708, if it is determined that thetemperature of the implantable pulse generator 104 or component thereofis not too high, then the process 700 proceeds to decision state 720,wherein it is determined if the implantable pulse generator 104 ischarging. In some embodiments, this determination can comprise a binarydetermination of whether charging is occurring or not, and in someembodiments, this determination can comprise a qualification of thedegree to which charging is occurring.

In some embodiments, the determination of decision state 720 cancomprise a binary determination of whether charging is occurring or not,and in some embodiments, this determination can comprise a qualificationof the degree to which charging is occurring. In one specificembodiment, decision state 716 can include determining if charging isoccurring and qualifying the degree to which charging is occurring. Inthis embodiment, decision state 716 can further include estimating thedegree to which the coil level of the charging coil of the charger 116can be decreased without ending charging and/or the degree to which adecrease in the coil level of the charging coil of the charger willimpact the effectiveness of the charging field.

If it is determined that the implantable pulse generator 104 ischarging, then the process 700 returns to block 702 and proceeds asoutlined above. In some embodiments, the return to block 702 can furtherinclude waiting a predetermined period of time before additional chargedata is received, or before received charge data is analyzed.

If it is determined that the implantable pulse generator 104 is notcharging, then the process 700 proceeds to decision state 722, whereinit is determined if the charging coil of the charger 116 is operating atits maximum level, which can be, for example, a preset upper limit. Thisdetermination can be made by identifying the present level of thecharging coil and comparing the present level of the charging coil tothe maximum possible level of the charging coil. If the present level ofthe charging coil is less than the maximum level of the charging coil,then the charging coil is not operating at its maximum level.Alternatively, if the present level of the charging coil is equal to themaximum level, then the charging coil is operating at the maximum level.

If it is determined that the charger 116 is operating at the maximumcoil level, then process 700 proceeds to block 724, wherein theindicators are controlled to direct the user to reposition the charger116 and/or to indicate the charger 116 has moved from its originalposition. After the indicators have been controlled, the process 700 canreturn to block 702 and proceed as outlined above. In some embodiments,and before returning to block 702, the process 700 proceeds to decisionstate 628 of process 600 in FIG. 9, and proceeds as outlined therein. Insuch an embodiment, after termination is indicated in block 638, process700 would then return to block 702 and proceed as outlined above.

Returning now to decision state 722, if it is determined that the chargelevel of the charging coil of the charger 116 is not operating at amaximum level, the process 700 proceeds to block 726, wherein the coillevel of the charging coil of the charger 116 is increased. After thecoil level of the charging coil of the charger 116 has been increased,the process 700 proceeds to block 724 and continues as outlined above.

With reference now to FIG. 12, a flowchart illustrating one embodimentof a process 1200 for adjusting the rotatable mount 146 of a charger 116is shown. In some embodiments, this process 1200 can be performed by acomponent of one or both of the charger 116 and the implantable pulsegenerator 104, including, for example, the processor of one or both ofthe implantable pulse generator 104 and the charger 116.

The process 1200 begins in block 1202, wherein a device, such as theimplantable pulse generator 104, is implanted. In some embodiments, thiscan include creating an incision in the skin, and a sub-dermal pocketfor receiving the implantable pulse generator 104.

After the device has been implanted, the process 1200 proceeds to block1204, wherein the charger 116 is positioned over, and/or proximate tothe device, which device can include the implantable pulse generator104. In some embodiments, this can include placing the charger 116proximate to the implantable pulse generator 104. This can furtherinclude, for example, securing the charger 116 to the patient via theretention feature 142.

After the charger 116 has been placed proximate to the device, theprocess 1200 proceeds to block 1206, wherein the acceptability of themagnetic coupling is identified. In some embodiments, this can includethe generation of a magnetic field of a first strength by the charger116, the detection of the strength of the magnetic coupling at theimplantable pulse generator 104, and the transmission of a signalindicating the strength of the magnetic coupling at the implantablepulse generator 104 to the charger 116. In some embodiments, thisidentification of the acceptability of the magnetic coupling can includedetermining a first orientation of the transmitting coil 350 withrespect to the receiving coil 250, which can specifically includeidentifying the angle between the axis 255 of the receiving coil 250 andthe axis 357 of the charge coil 350.

After the acceptability of the strength of the magnetic coupling hasbeen identified, the process 1200 proceeds to decision state 1207,wherein it is determined if the strength of the magnetic coupling isacceptable. In some embodiments, the acceptability of the strength ofthe magnet coupling can be determined by compared the measured strengthof the coupling to one or several thresholds. If the measured strengthexceeds the threshold value, then the strength of the magnetic couplingcan be acceptable. Conversely, if the measured strength does not exceedthe threshold value, then the strength of the magnetic coupling can beunacceptable. In some embodiments, and as a part of decision state 1207,an indicator of a degree of acceptability and/or unacceptability can beprovided to the user of the charger 116, which indicator can be a visualand/or audible indicator. In some embodiments, the indicator can belocated in the charger 116, and in some embodiments, the indicator canbe, for example, communicated to another device such as, for example, asmartphone, a tablet, a computer, or the like. In some embodiments, thiscan include, for example, an indication of the degree to which therotatable mount 146 should be re-oriented, and direction in which therotatable mount 146 should be re-oriented.

If it is determined that the strength of the magnetic coupling isacceptable, then the process 1200 proceeds to block 1208, wherein therotatable mount is locked in place. In some embodiments, the rotatablemount 146 can be locked in place via the lock feature 808.

Returning again to decision state 1207, if it is determined that thestrength of the magnetic coupling is unacceptable, then the process 1200proceeds to block 1210, wherein the rotatable mount 146 is re-oriented,in other words, wherein the rotatable mount 146 and the thereto attachedtransmitting coil 350 are placed in a second orientation with respect tothe receiving coil 250. In some embodiments, the re-orientation of therotatable mount 146 can likewise re-orient the transmitting coil 350. Insome embodiments, the angle between the axis 255 of the receiving coil250 and the axis 357 of the transmitting coil 350 is smaller when thetransmitting coil 350 is in than second orientation than when thecharging coil is in the first, original orientation.

After the rotatable mount 146 has been re-oriented, the process 1200returns to block 1206 and proceeds as outlined above. In someembodiments, through process 1200, the transmitting coil 350 can beoriented with respect to receiving coil 250 such that the axes 255, 357of the charging coils 250, 350 are acceptably parallel such that thestrength of the magnetic coupling between the charging coils 250, 350exceeds the threshold of decision state 1207. Alternatively, in someembodiments, process 1200 can be repeated until the angle between axis255 of receiving coil 250 and axis 357 of transmitting coil 350 isminimized.

In the foregoing specification, the invention is described withreference to specific embodiments thereof, but those skilled in the artwill recognize that the invention is not limited thereto. Variousfeatures and aspects of the above-described invention can be usedindividually or jointly. Further, the invention can be utilized in anynumber of environments and applications beyond those described hereinwithout departing from the broader spirit and scope of thespecification. The specification and drawings are, accordingly, to beregarded as illustrative rather than restrictive. It will be recognizedthat the terms “comprising,” “including,” and “having,” as used herein,are specifically intended to be read as open-ended terms of art.

What is claimed is:
 1. A method of charging an implantable device, themethod comprising: positioning a charging head comprising a transmittingcoil attached to a retention feature proximate to an implantable devicecomprising a receiving coil; determining a first orientation of thetransmitting coil with respect to the receiving coil; and rotating theattached transmitting coil until the transmitting coil has a secondorientation with respect to the receiving coil, wherein the rotation ofthe transmitting coil is along a plane substantially parallel to a planedefined by the receiving coil.
 2. The method of claim 1, wherein thetransmitting coil has a longitudinal axis and at least one wire wrappedaround the longitudinal axis.
 3. The method of claim 2, wherein thereceiving coil has a longitudinal axis and at least one wire wrappedaround the longitudinal axis.
 4. The method of claim 3, whereindetermining the first orientation of the transmitting coil with respectto the receiving coil comprises determining an angle between thelongitudinal axis of the transmitting coil with respect to thelongitudinal axis of the receiving coil.
 5. The method of claim 4,wherein the angle between the longitudinal axis of the transmitting coilis non-parallel with the longitudinal axis of the receiving coil in thefirst orientation.
 6. The method of claim 4, wherein an angle betweenthe longitudinal axis of the transmitting coil and the longitudinal axisof the receiving coil in the second orientation is less than the anglebetween the longitudinal axis of the transmitting coil and thelongitudinal axis of the receiving coil in the first orientation, andwherein a charging efficiency in the first orientation is less than acharging efficiency in the second orientation.
 7. The method of claim 3,wherein rotating the transmitting coil until the transmitting coil has asecond orientation with respect to the receiving coil comprisesdetermining when an angle between the longitudinal axis of thetransmitting coil and the longitudinal axis of the receiving coil isminimized.
 8. The method of claim 7, wherein the second orientation isreached when the angle between the longitudinal axis of the transmittingcoil and the longitudinal axis of the receiving coil is minimized.
 9. Animplantable device comprising: a processor configured to control anoperation of the implantable device and to generate a plurality ofelectrical impulses for stimulating a peripheral nerve of a patient; alead configured for placement proximate to a peripheral nerve; an energystorage device configured to store energy; and a charging coilcomprising: an elongate core having a first end, and second end, and alongitudinal axis extending therebetween; and a wire wrapped in aplurality of coils around the elongate core and the longitudinal axis ofthe elongate core; wherein the charging coil is attached to an outersurface of a body of the patient, the charging coil being rotatable withrespect to a retention feature, wherein the charging coil is rotatablealong a plane substantially parallel to a plane defined by the outersurface of the body of the patient.
 10. The implantable device of claim9, wherein the wire comprises litz wire.
 11. The implantable device ofclaim 9, wherein the elongate core comprises a soft ferrite material.12. The implantable device of claim 9, wherein the charging coil has a Qfactor of at least
 70. 13. The implantable device of claim 9, whereinthe charging coil has a Q factor of at least
 80. 14. The implantabledevice of claim 9, wherein the charging coil further comprises acapacitor electrically connected to the wire.
 15. The implantable deviceof 14, wherein the capacitor comprises a high Q COG capacitor.
 16. Theimplantable device of 14, wherein the capacitor is located on thecharging coil.
 17. The implantable device of 14, wherein the capacitoris located proximate to the charging coil.
 18. The implantable device of14, wherein the capacitor is positioned so as to create a high Q tankcircuit.
 19. A charging system comprising: an implantable devicecomprising: a receiving coil having: an elongate core having a firstend, a second end, and a longitudinal axis extending therebetween; and awire wrapped in a plurality of coils around the elongate core and thelongitudinal axis of the elongate core; and a charging head comprising:a transmitting coil having: an elongate core having a first end, asecond end, and a longitudinal axis extending therebetween; and a wirewrapped in a plurality of coils around the elongate core and thelongitudinal axis of the elongate core; wherein the transmitting coil isattached to a retention feature configured to be placed proximate to theimplantable device, the transmitting coil being rotatable with respectto the retention feature, wherein the transmitting coil is rotatablealong a plane substantially parallel to a plane defined by the receivingcoil.
 20. The charging system of claim 19, wherein the receiving coilcomprises a capacitor electrically connected to the wire of thereceiving coil.
 21. The charging system of claim 19, wherein thecharging head comprises a rotatable mount.
 22. The charging system ofclaim 21, wherein the transmitting coil is attached to the rotatablemount.
 23. The charging system of claim 22, wherein the rotatable mountis rotatable between a first position and a second position.
 24. Thecharging system of claim 23, wherein the rotatable mount is lockable inthe first position and in the second position.
 25. The charging systemof claim 22, further comprising circuitry configured to detect anangular position of the receiving coil with respect to the transmittingcoil.
 26. The charging system of claim 25, wherein the circuitryconfigured to detect an angular position of the receiving coil withrespect to the transmitting coil are in the charging head.
 27. A methodof charging an implantable device, the method comprising: positioning anexternal charger on an outer surface of a person's body proximate animplanted electrical pulse generator, the external charger including ahousing, a retention feature, and a charging coil, wherein the chargingcoil is rotatable with respect to the retention feature, the implantedelectrical pulse generator including a charging coil; fixing theposition of the external charger on the outer surface of the person'sbody; and while the external charger is fixed on the outer surface ofthe person's body, rotating the charging coil of the external charger tochange an orientation of the charging coil of the external chargerrelative to the charging coil of the implanted electrical pulsegenerator, wherein the rotation of the charging coil is along a planesubstantially parallel to a plane defined by the outer surface of theperson's body.
 28. The method of claim 27, wherein the implantedelectrical pulse generator further comprises at least one electrodeimplanted proximate a peripheral nerve of the person.